1. The Technical Field
The present invention relates in general to multiwall pinch bottom bags, of the type, which are typically fabricated as a tube formed from one or more paper plies.
2. The Prior Art
Multiwall bags, fabricated as tubes formed from a plurality of paper plies, are known. Typically, the ends of the tubes are cut, so that when the end or ends of the bag are flattened, the plies of the bag, on both sides of the mouth opening of the bag, are provided with steps. The stepped-end cut pattern creates a closure flap on one side (the xe2x80x9chighxe2x80x9d side) of the mouth opening of the bag. The side of the bag on the opposite side of the mouth opening is the xe2x80x9cshortxe2x80x9d side. Closure of the bag is typically accomplished by applying adhesive (e.g., hot melt or sonically activatable adhesive) to the outer surface of the short side of the bag. In addition to, or alternative to, providing adhesive on the face of the bag, adhesive may be applied to the inside surface of the closure flap. When the closure flap is folded over the mouth opening of the bag, preferably, the stepped plies of the flap substantially align with and overlie correspondingly cut steps in the bag plies on the face of the bag on the short side of the mouth opening.
Closing the bag by simply folding and adhesively affixing the flap provides the pointed, pinch bottom closure. The opposite end of the bag may be likewise provided with a pinch bottom closure, or it may be closed and sealed in a different configuration, such as a diamond- or rectangular configuration, so that the pinch xe2x80x9cbottomxe2x80x9d may actually be the top of the bag, as may be found commonly in bags containing dry granular material, like dog food or cat litter.
In addition to having paper plies, one or more plies, typically the innermost one or more plies, may be fabricated from a thin plastic material, or may be coated with a resinous material, to provide a degree of moisture resistance to the finished bag.
While the bag may be formed initially as a simple flattened tube, with folded closure flaps, pinch bottom bags are also known, in which typically both sides of the bag are gusseted, so that there are inward V-folds at each side of the bag, prior to folding the closure flap. Often, because of the stepped-end cutting of the bag plies, in the region of the gussets, the bag material extends beyond the topmost edge of the innermost ply of bag material on the xe2x80x9cshortxe2x80x9d side of the mouth opening, so that in folding over and affixing the closure flap, the tops of the gussets are likewise folded over and captured by the closure flap. Such a prior art gusseted pinch bottom bag is disclosed in Goodrich, U.S. Pat. No. 4,008,850.
When such a bag is closed and sealed, the folded over closure is typically quite strong, and requires cutting of the bag plies, below the folded over and sealed closure, in order to gain access to the contents of the bag.
In order to facilitate opening of such bag structures, multiwall bag structures are known that incorporate tear structures that may be formed by extended perforations, usually in parallel pairs, through one or more plies of the bag, or by providing ripcord structures that are embedded in the bag plies, that lead to pull tabs, that extend to the outer surface of the bag. Such prior art bag opening structures are disclosed in such references as EP 0 596 747 A1; Rodkey, U.S. Pat. No. 3,272,424; Allen, U.S. Pat. No. 2,560,535; Brady et al., U.S. Pat. No. 2,870,955; Vogt, U.S. Pat. No. 4,088,264; Robinson, U.S. Pat. No. 4,557,385; Jacobs, U.S. Pat. No. 4,768,654; Lepisto et al., U.S. Pat. No. 4,483,445; and Thrall, U.S. Pat. No. 5,281,027.
Whether opened by the simple expediency of a cutting or piercing implement, or whether opened through a prior art opening mechanism such as those disclosed in the aforementioned references, typically, opening of the bag either requires substantial effort and/or results in a ragged opening that may include opening the entire mouth of the bag. When the contents of such an opened bag are poured out, because the entire mouth has been opened there is little control over the contents, and undesired spilling of the contents may occur.
It would be desirable to provide a multiwall bag formed from one or more plies of bag material, of which at least the outermost ply or plies is/are formed from paper, that has an easy open feature, to enable facilitated access to the contents of the bag, without requiring the use of a cutting or piercing implement.
It would also be desirable to provide a multiwall bag, such as a pinch bottom closure bag, that is provided with a secure closure, but which is also provided with an easy open feature, which creates a controlled opening of only a portion of the mouth of the bag, for controlled dispensing of the contents of the bag.
These and other desirable features of the present invention will become apparent in light of the present description, claims and drawings.
The present invention is directed to a bag apparatus for the containment of material, comprising a tubular body, fabricated from at least one ply of material. The tubular body has a longitudinal axis. The tubular body also has a first end configured to form an elongated mouth opening. When in a flattened condition, the tubular body has first and second opposing sides adjacent the elongated mouth opening, and first and second side edges.
One of the opposing sides forms an upper step and the other of the opposing sides forming a lower step. A fold line extends across the tubular body, transversely to the longitudinal axis, wherein the elongated mouth and portions of the lower step are disposed longitudinally between the upper step and the fold line.
A portion of the lower step, disposed adjacent the first side edge of the tubular body, extends further longitudinally away from the fold line, than other portions of the lower step.
A tear string member is disposed transversely across the first end of the tubular body, and extends across the longitudinally extending portion of the lower step, laterally inwardly from the first side edge of the tubular body toward the second side edge of the tubular body. A line of weakness is disposed in at least one layer of the upper step of the tubular body, the line of weakness being substantially aligned with that portion of the tear string member that extends across the longitudinally extending portion of the lower step of the tubular body, and extending at least from the first side edge of the tubular body, laterally inwardly toward the second side edge of the tubular body.
In a preferred embodiment of the invention, the upper step is folded about the fold line, over and against the lower step and affixed thereto, the tear string member and the line of weakness remaining in substantially alignment, with the tear string member being in longitudinally spaced position with respect to the fold line.
In a preferred embodiment of the invention, the at least one ply of material is paper material. Preferably, the tubular body is formed from three plies of material.
In a preferred embodiment of the invention, the tubular body further comprises at least one inwardly folded gusset. The at least one inwardly folded gusset extends inwardly from the first side edge of the tubular body. In such an embodiment of the invention, the longitudinally extending portion of the lower step of the tubular body extends longitudinally beyond at least portions of the at least one inwardly folded gusset.